Hydraulic brake



June 26, 1923.

M. LOUGHEAD HYDRAULIC BRAKE Filed Jan. 23, 1922 v 111,460,164 UNI'TED STATES; ATENT; OFFICE A I MALCOLM LOUGHE'AD, or nn'rnorr, meme, c- -assrenoa 'ro roan, WHEEL HYDRAULIC BRAKE COMPANY, or Los ANcnLEs, CALIFORNIA, ACOBPOBL TION OFCALIFORNIA. V

nrnnaumc seams,

Application filed January as, 1922. seriarm 531,142.

To all whom it may concern: Figure 1 is a more or less diagrammatic Be it known that I, MALCOLM LOUGHEAD, view illustratin an automotive vehicle a citizen of the United States, and resident equipped with a braking system embodying of Detroit, in the county of Wayne and my present invention, and 5 State of Michigan, have invented a certain Figure 2 is a vertical sectional view of 60 new and useful Improvement in Hydraulic the control valve. Brakes, of which the following is a full, Similar characters of reference refer to clear, concise, and'exact description, refersimilar parts in the above figures. ence being had to the accompanying draw- In Figure 1 Ihave illustrated an automoin s, forming a part of. this specification. tive vehicle'compri sing a plurality of brake 65 lVly invention relates to hydraulic brakes drums 3-3 (one front and one rear brake for vehicles, and is particularly concerned drum bein illustrated) each brake drum bewiththe provision of-novel means for c011 ing provi ed with a brake band 3*. The trolling the application of pressure to the brake bands are adapted to be drawn into i j hydraulically operated devices which are braking relation with the brake 'drumsupon 7 mechanically connected with the brake, the actuation of the'hydraulically operated bands, or brakes per se. devices H. Theseveral devices 4: are con- Generally speaking, abraking system emvnected with a pedally actuated fluid combodying my invention comprises brake pressor 5 through conduits 6-6, the control bands, or their equivalent, hydraulically opvalve Vand the conduit 7 which is inter- 7 erated devices which are mechanically conposed between the compressor and the connected with the brake bands, a manually or trol valve. c pedally operated fluid compressor, and fluid It will be unnecessary in this specificaconnections between the compressor and the tion to illustrate or describe the details of hydraulically operated devices aforesaid. I the'compressor 5, or the details of the de- 8 have discovered that a system of this. kind vices 4.4, nor will it be necessary or deis greatly improved if it comprises means 'sirable to-illustrate the manner of mounting for preventing an excessively rapid increase the devices H in operatin relation to the in the pressure applied to the hydraulically brake bands. The details 0 the compressor operated devices associated with the brake are illustrated in my co-pending' applicabands after such hydraulically operated detion, Serial No. 531,144 filed January .23, vices have been actuated to that extent nec- 1922 and the structural details of the deessary to take up the slack in the brake vices 44 and the conduits 6-6 are fully bands, and in the mechanical connection beshown and described in my co-pending ape tween such bands and the hydraulically opplication, Serial No. 531,145 filed January 90 erated actuating devices therefor. 23, 1922. 'For the .purposeof the present One of the salient features of my present specification, it will suffice to state that actuinvention is a control valve of novel conation of the. compressor 5 transmits fluid struction, which is interposed in the fluid pressure to devices 4 --4: through the prespressure line between the compressor and sure linecomprising the conduit 7 the con- 95 the hydraulically operated devices which I trol valve and the several conduits 6-6.

are associated with the several brake bands. Referring now to Figure 2, it will be noted This valveautomatically functions to perthat the control valve V comprises an openmit comparatively free communication beended housing 8, which is provided intertween the compressor and the hydraulically mediate .its ends with an outlet port 9, operated devices until a definite predeter- Threaded into one end of the housingis a. mined pressure has been created in the p-resplug" 10 which is formed integral with a sure line. The valve, however, functions coupling nipple 11. A bore 12 extends normally to restrict communication between through plug 10 and the nipple 11, as illusv the compressor and the hydraulically opera trated, Nipple 11 is adapted to be suitably 5 ated devices. The advantages'which; may connected with conduit 7, and outlet'port 9 be attributed to the control valve will more communicates with the conduits 6-6 which fully hereinafter appear. lead to the brake band operating devices In the accompanying drawing illustrating my invention,

I now call attention to the fact that hous- .25 the housing cap 20. -Downward movement housing 8 is a plunger which comprises the shoulder at 15, against which bears the lower ing 8 is provided with co-axial bores 8 and 8", and with an intermediate conical or tapering bore 8, which communicates with' both the bores 8 and 8". Mounted in the head 14, the lower end of which is'preferably beveled to a circular edge as indicated at 14% The; plunger is provided with a of a pair of reversely disposedcup leathers '16- 16, the cup leathers being arranged snugly to fit in bore '8. Both cup leathers. are disposed around the plunger stem 14". Loosely disposed aroundthe stem 14" is a; block 17,- the lower end of which is reduced to fit within the upper cup leather 16. A compression spring 18 acts between the upr end of the block 17 and'theunder surace of an externally threaded annulus 19, the annulus co-operating with internal screw threads at the upper end of the bore8. The normal compression of spring 18 is determined by the adjustment of the annulus 19. "The upper end of the plunger stem extends freely through a "central opening in of the plunger is limited'by engagement of the housing cap with the nut 21 and upward movement of the plunger islimited by engagement of the housing cap with the nut 22. Nut 21 may be provided'with a lock to the brake'bands in particular. i As soon as'thepressure in the system has been raised I to a predetermined degree, say, for instance, I to a pressure ofeight'y pounds per square.

fluid against the several inch, thepressure o parts of theplunger structure overcomes the adjusted pressure of the spring 18, and the plunger -m 'ove' s upwardly to a; position; ,wherein the nut 22 lies against the cap 20.

With the lunger in this, its upper, posltion, the circu ar .ed hence with the p unger in its upper. position 14* lies within bore 8',

communication between bore .12 and port 9 is restricted to a;..much greater extent than is the cas'ewhen the plunger occupies its lower position. The restriction in the com- .municat'ionbetween the compressor and the devices 4 -4 which is effected as soon as the pressure exceeds a predetermined figure adequately protects the car and brake bands from that injury which would result froman extremely rapid rise in the pressure applied to the devlces 4-4.

When the pressure upon the compressor pedal is relieved, the pressure in the system 1 drops a few pounds, and the plunger is forced down to its normal position by the spring 18, and thus the control valve in no way impedes quick releasal of the brakes. Automobile drivers by reason of habit acquired'throughthe use of ordlnary foot nut 21- if desired. It should be noted that rak s re inclin d t g v h mpr sor the sleeve 23 is disposed around the plunger stem, and'is interposed between block 17 and nut 22. Tightening of the nut 22 thus serves firmly to clamp sleeve 23, block 17 and the cup leathers 16-16 upon the plunger proper.

In a valve of the dimensions illustrated in Figure 2, the area of the annular space between the circular edge 14 and the housing wall which lies therearound is equal to the cross-sectional area of a circular opening having a diameter of one-fourth inch, when the plunger is in its lower position. When conduits eading to the brakeband' operating devices As soonv as the devices 44 have responded to a degree suflicient to take up the slack in the-brake bands, the pressure on the several conduits interposed betweendevices-H and the compressor rises very rapidly. -A -too rapid application of pressure to the brakin devices 4-4 is apt to 1 5 result injury to t 0 vehicle in general, and

pedal a violent thrust when thebrakes are to be applied. Such practice would be injurious' to the car, and in some cases actually very dangerous, were it not for the presence of my control valve which, regardless of the speed at which the compressor pedal is operated, automatically prevents an excessively rapid rise in the fluid pressures applied to the brake band operating devices 44.

Having thus described my invention,

what I claim is new, and desire to secure by' Letters Patent of the United States is:

1. A braking apparatus comprising in combination, a fluidressure actuated brake operating device, a uid compressor, a fluid pressure line extending between the com pressor and the saidbrake operating device, and means interposed in said fluid pressure line and controlled by the pressure existing in said line arranged to partially close-the communication between the compressor and thefluid pressure actuated brake operating device when the .fluid in said line has attained a predetermined pressure.

2. A braking apparatus comprising a fluid compressor, a fluid-actuated brake operating device, a line through which fluid is transmitted from said compressor to said brake operating device, and means, subjectto the pressure developed by said compressor,- arranged to partiallyclose the communication vbetween the compressor and the brake operating device aforesaid when the fluid in said line has attained a pred'etermined pressure.

3. A braking apparatus comprising in combination a fluid compressor, a fluidpressure actuated brake operating device, a pressure line extending between said compressor and valve constituting a part of said pressure line, said valve comprising a fluid-actuated movable element which in one of its positions permits substantially unrestricted passage of fluid through the valve, and which when in another position partially closes the channel for the passage of fluid through the valve, and spring means normally holding said movable element in its first-mentioned po'sitio'n,-said spring means yielding to permit the movable element to assume its restrictedYposition when a predetermined fluid pressure is exertedon' said movableelement. 7

4.111 a vehicle braking system, a plurality of brake hands, a fluid-actuated operating device associated with each brake band, a fluid compressor, a fluid pressure control valve, and a conduit affording communication between the compressor and the control valve, conduits aifording communisaid brake operating device, a

position wherein cation between said control valve and said brake band operating devices,'said control valve comprising fluid pressure actuated means which normally permits comparatively free communication between the compressor and brake operating devices, but functions to partially close such communication when a predetermined fluid pressure has been attained in said conduits.

5. In abraking system of the class described, a control valve comprising a housing having an opening therein provided with inlet and outlet ports, a movable restricting 

